A temporary one that you're expected to remove as soon as you've created the admin user(s) you need, but yes. It should only be there during initial setup and ideally removed before the server is ever exposed to the internet.
Yes because having a user remember to do something is a great line of defense, better than encrypting it from the get go. It should just be encrypted in the file.
I think that's the way both Splunk and JFrog work -- you generate or enter a password into the key field in a YAML file somewhere, start the service, and next time you come back the field's been encrypted.